Maxima Function
ssort (string)
ssort(string,test)
Returns a string that contains all characters from string in an order such there are no two successive characters c and d such that test (c, d) is false and test (d, c) is true.
Default test function for sorting is clessp.
The set of test functions is {clessp, clesspignore, cgreaterp, cgreaterpignore, cequal, cequalignore}.
(%i1) ssort("I don't like Mondays."); (%o1) '.IMaddeiklnnoosty (%i2) ssort("I don't like Mondays.",'cgreaterpignore); (%o2) ytsoonnMlkIiedda.'